Air conditioning system for dwellings



R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLING-S April s, 1958 Filed June 25, 19565 Sheets-Sheet 1 /jj v.4 if

INVENTOR.

19(140/7 c sch/m;

R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLINGS s Sheets-Shet 2 April 8, 1958Filed June 25, 1956 JNVENTCR. Aa/ph C. Sc/Micki? April 1958 R. C.SCHLICHTIG AIR CONDITIONING SYSTEM FOR DWELLINGS Filed June 25, 1956 5Sheets-Sheet 3 INVENTOR. Raw a say/m April 1958 R c. SQHLHCHTIG2,829,504

AIR COND ITIONING SYSTEM FOR DWELLINGS Filed Jfine 25, 1956 5SheetsSheet 4 I I I April 8, 1958 R. c. SCHLICHTIG 2,829,504

AIR CONDITIONING SYSTEM FOR DWELLING-S Filed June 25, 1956 5Sheets-Sheet 5 75 Ranks/17y Va/l e 2 V United States Patent AIRCONDITIONING SYSTEM FOR DWELLINGS Ralph C. Schlichtig, Dishman, Wash.

Application June 25, 1956, Serial No. 593,409

Claims. c1. 62--3) The present invention relates to improvements in anair heating and cooling system utilizing a reversibleexpansion-compression system which will, in cold weather, a

draw heat from outdoor air and supply it to a building unit aircirculation system, and which will, during warm weather, draw heat fromthe building unit air circulation system and supply it to outside air.

I am aware that such reversible expansion and compression systems areknown in the air conditioning field. The basic combination in such asystem comprises an evaporator, a compressor charged with gas therefromand a condenser which receives compressed gases from the compressor.When used for heating, the evaporator is positioned in contact withoutside air to cause the fluid to pick up heat from the air. The fluidis then compressed to a higher pressure, and at this higher pressure,condensed to release the heat vaporization at a higher temperature inthe building unit. When the system is used for cooling, the operation isreversed so that evaporation takes place in the condenser andcondensation takes place in the evaporator, whereby heat is withdrawnfrom the building unit. and added to the outdoor air.

Such systems have several inherent weaknesses which have prevented theirsuccessful operation in colder climates. Perhaps the most seriousweakness is the rapid decrease in heat delivering capacity of the systemas the heat supplying outdoor air drops to a low temperature,

resulting in a drastic reduction of vapor pressure of the fluid in theevaporator and a consequent reduction of the charge in the compressor.Another weakness lies in the fact that as the temperature ofthe outerair goes down, more and more useful heat is carried back from theradiating condenser to the evaporator by the returning fluid, therebyreducing the net heat absorbed. A third weakness lies in the fact thatwhen the outside air is near freezing, ice will be deposited on theevaporator, plugging it up and reducing its efficiency.

It is an object of the present invention to provide anexpansion-compression system, reversibly operable to provide heating orcooling for a building unit, which is operable to draw heat from outsideair partially warmed and dried by heat escaping from the building unitand also to draw heat from mild ground air drawn from a ground well.

A further object of the invention isto provide such a system having acompressor super charging system operated by heat returning with thefluid from the radiating condenser and additional heat from a watersource.

A still further object of the invention is to provide such a systemhaving an automatic rapid defrosting mechanism for the evaporator whichutilizes the mild air drawn from the ground well and a water spray tomelt the ice from the evaporator.

The nature and advantages of the invention will appear more clearly fromthe following description and the accompanying drawings, wherein apreferred form of the invention is shown. It should be understood,however,

2,829,504 Patented Apr. 8, 1958 that the drawings and description areillustrative only, and are not intended to limit the invention exceptinsofar as it is limited by the claims. t i

In the drawings: 3

Figure 1 is a diagrammatic cross sectional view of a building unitprovided with a heating and cooling system in accordance with myinvention;

Figure 2 is a diagrammatic view of my heating and cooling systemillustrating its utilization as a heating plant for the building unit;

Figure 3 is a diagrammatic view similar to Figure 2 but showing myinvention utilized for cooling;

isure 4 is a sectional view taken on the line 4-4 of Figure 2,illustrating the positioning of the elements of the system in the airducts of the heating and cooling unit;

Figure 5 is a sectionaal view taken onthe line 5-5' of Figure 2; t

Figure 6 is a wiring diagram showing the electrical connections for theheating and cooling system;

Figure 7 is a wiring diagram illustrating a slightly modified electricalcircuit; and

Figure 8 is a fragmentary sectional view illustrating the reversingvalve I employ in my system.

Referring now to the drawings, my invention is shown in Figure 1 asinstalled in a building unit 10. having a basement 11, a dwelling area12 thereabove, an attic area 13 above the dwelling area, and a roof 14covering the attic area. My heating and cooling unit generally indicatedat 15 is located in the basement 11; The unit 15, shown more in detailin Figures 2 and 3 is comprised essentially of a compressor 16 driven byan electric motor 17 (see Figures 6 and 7), an evaporator 18 comprisedof coiled tubing having thin heat conducting fins 19 thereon, and acondenser 20, also comprised of coiled tubing having heat conductingfins 21 thereon. The evaporator 18 and condenser 2%) are connected tothe compressor 16 through a reversing valve generally indicated at 22and described more in detail later herein.

The condenser 26 is positioned within a hot air bonnet 23 mounted atopthe unit 15. The bonnet 23 is connected by a hot air duct 24 to thedwelling area 12 of the building 10. A cold air return duct 25 leadsback from the dwelling area 12 to the bonnet 23. The bonnet 2.3 and theducts 24 and 25 (it being understood, of course, that there are amultiplicity of each of the ducts 24 and 25 to supply air circulationthroughout the building.) comprise the hot air circulation system forthe building unit 1th. This system may be operated by gravity.

or may be a forced air system in which case a circulation fan 26,positioned in the bonnet 23, is employed.

The evaporator 18 of the unit 15 is positioned within a chamber 2'7which is supplied with air from a duct 28. The unit is designed toextract heat from outside air, so the duct 28 is opened to the outsideair. I have found that the efficiency of the system can be greatlyincreased if the duct 28 is opened into the attic 13 of the building 10where it can gather outside air entering the attic 13 throughventilating openings 29, which air has already been somewhat warmed anddried by heat escaping from the dwelling area 12 below. This air isdrawn into the duct 2% and through it to the chamber 27 by a fan 30positioned in the chamber 27. After the air has flowed over theevaporator 18, it is exhausted to the outside by an exhaust duct 31;

Referring now more particularly to Figures 2 and 3, the compressor 16 isshown as having a cylinder 32 in which a piston 33 reciprocates,alternately reducing the cylinder space to compress and exhaust a chargeof refrigerant fluid and enlarging the cylinder space to reduce thepressure therein and draw in a new charge of refrigerant. Therefrigerant may be anysuitable fluid such as that sold under the tradename Freon. A pipe 34 extends from the cylinder 32 and has therein acheck valve 35 which permits exhaust flow from the cylinder 32 but whichprevents return flow. The pipe 34 connects to two pipes 36 and 37 whichlead to opposite ends of the reversing valve 22. The pipes 36 and 37have solenoid operated shut-off valves 33 and 39 therein. The reversingvalve 22, shown diagrammatically in Figures 2 and 3, is shown in detailin Figure 8. The valve 22 comprises two opposed valves 40 and 41connected by a connecting rod 42. The valves 40 and 41 are cup-sl1apedin cross section and have openings 43a in their side faces. Each valve40 and 41 has an inwardly extending skirt 42b thereon as shown in Figure8. The valves 40 and 41 are slidably mounted in cylinders 40a and 41awhich have valve seats 40b and 41b therein. The valves 43 and 41 are soarranged thatwhen one is seated in its valve seat, the other ispositioned near the outer edge of its cylinder. Each of the cylinders40a and 41a has a port 400 and 410 at its outer end to which the pipe 36or 37 is connected. The cylinders 40a and 41a have second ports 40d and41d near their inner ends to which the evaporator 18 and the condenser20 are connected, the condenser 24 being connected to the port 40a andthe evaporator 18 being connected to the port 41d. The cylinders 40a and41a have enlarged portions 4% and 41e adjacent the ports 40d and 41a.The intermediate portion of the reversing valve 22 between the cylinders40a and 41a is connected by a return line 43 which leads back to theintake port of the compression cylinder 32. A check valve 44 in the line43 prevents exhaust flow from the cylinder 32 into the line 43.

With the construction just described, manipulation of the two pilotoperating solenoid valves 38 and 39 causes pilot operation of thereversing valve 22 to shift positively to direct compressed refrigerantinto either the condenser 20 or the evaporator 13 without waiting forpressure to become equalized on the two sides, and to direct refrigerantfrom the remaining unit back into the compression cylinder 32. When thesolenoid valve 38 is open and the solenoid valve 39 closed, as shown inFigures 2 and 8, the compressed refrigerant in the pipe 34 is free toenter the cylinder 40a of the valve 22 but cannot enter the cylinder41a. The high pressure fluid flows into the cup of the valve 40 andcauses it to move positively against its seat 40b. This positions theopenings 42a in the enlarged portion 4% of cylinder 40a and allows thecompressed refrigerant to flow through the port 40d, thereby admittingthe compressed refrigerant to the condenser 20. When the valve 40 is soseated, the valve 41, not subjected to pressure since the solenoid valve39 is closed, is forced toward the outer end of the cylinder 41a. Inthis position the refrigerant in the evaporator 18 is free to enter theport 41d, pass into the central portion of the valve 22, and through theline 43 to the compression cylinder 32. When the solenoid valve 33 isopened and the solenoid valve 38 is closed, as in Figure 3, the valve 22is reversed and compressed refrigerant flows into the evaporator 18while refrigerant in the condenser flows into the return line 43. Inthis instance, the functions of the members 18 and 20 are reversed, themember 20 acting as an evaporator and the member 18 acting as acondenser. The skirts 4212 are so positioned that as the valve 41 or 41moves toward its seat 40b or 41b, the skirt 42b closes the opening inthe seat before the slot 42a is moved to the enlarged portion 40:: or41e of the cylinder 40a or 41a. This prevents refrigerant from flowingdirectly from either line 36 or 37 into the return line 43.

The unit, set up for operation as shown in Figure 2, acts as a heatingsystem. The compressed refrigerant is indicated in the drawings bythickly dotting the pipe area. The evaporated refrigerant is indicatedby lightly dotting the pipe area. The condensed refrigerant is indicatedby double cross hatching the pipe area. Refrigerant in the compressioncylinder 32 is compressed by the piston 33 and fed through the pipes 34and 36, and the cylinder 40a, to the condenser 20. The compressedrefrigerant is at this time at a relatively high pressure andtemperature. As the refrigerant flows through the condenser, the coolerair in the bonnet condenses it, lowering the pressure and temperature.Condensation, of course, releases heat from the refrigerant which istransferred to the air in the bonnet 23. After the refrigerant haspassed through the condenser 20, it flows through a pipe 45 which joinsanother pipe 46. Reverse flow in the pipe 45 is prevented by a checkvalve 47. When the refrigerant, now a liquid and having experienced apres-sure and temperature drop but still relatively warm, reaches thepipe 46, most of it flows into a receiving vessel 48, but due to acapillary restriction 46a in the pipe 46 between the vessel 48 and theconnection of the pipe 45, a portion of the refrigerant flows to a supercharging evaporator to be described later herein. Liquid reaching thevessel 48 is prevented from flowing in reverse by a check valve 46!) inthe line 46.

The liquid in the receiving vessel 48 flows out through a line 49 to aheat exchanger 50, the function of which will be described later herein.In the heat exchanger 50, the temperature and pressure of therefrigerant are lowered. From the exchanger 50, the refrigerant flowsthrough a pipe 51 which leads to the low temperature, low pressure,evaporator 18. A thermal regulating expansion valve 52 in the pipe 51 atthe connection thereof with the evaporator 18 expands the now coldrefrigerant into a vapor. The valve 52 is not shown in detail since itis well known and in common use in the refrigeration industry. A checkvalve 53 in the line 51 ahead of the valve 52 prevents reverse flow.

As hereinbefore described, the evaporator 18 is positioned in thechamber 27 and in a stream of outside air. Heat from this air isabsorbed by the expanding refrigerant in the evaporator 18. Thevaporized refrigerant is drawn from the evaporator 18 through thereversing valve 22 and into the return line 43 to the compressioncylinder 32. As the piston 33 moves down in the cylinder 32, a charge ofthis vapor is drawn into the cylinder 32.

The portion of the system heretofore described operates in substantiallythe same manner as a common heat pump. I have found, however, that undercommon cold weather conditions, the refrigerant vapor in the evaporator18 is at such a low pressure, for example, about 18 p. s. i. absolute inthe case of Freon when the outside air is at 5 F., that the chargeadmitted to the cylinder 32 on each intake stroke of the piston 33 istoo small to cause the condenser 20 to radiate enough heat tosufiiciently warm the air in the bonnet 23. I therefore provide asupcrcharging apparatus for the cylinder 32. I have found that the relatively warm liquid in the receiving vessel 48 is subject to a certainamount of evaporation and produces vapor of considerably higher pressurethan that in the evaporator 13. This vapor is utilized to superchargethe cylinder 32 by providing a line 54 from the receiving vessel 4'3 toa port 55 near the bottom of the cylinder When the piston 33 reaches thebottom of its stroke this port 55 is uncovered, and the higher pressurevapor from the line 54 rushes in to increase the vapor charge. Byproviding a venturi restriction 56 in the line 54, and by providing aconnecting line 57 from the return line 43 to the venturi restriction56,the rush of vapor through the line 54 and through the venturirestriction 56 is made to draw additional vapor from the evaporator 18through the line 57 by venturi effect to further increase the charge inthe cylinder 32. With this construction the heat carried from thecondenser 20 is utilized to increase the charge of the cylinder 32.

To further supercharge the cylinder 32, a supercharging evaporator 58 isutilized. This evaporator 58 is connected to the line 46 and receivesthat portion of the refrigerant from the line 45 which is diverted byresistance to flow at the restriction 46a. A thermal regulatingexpansion valve 59 expands the refrigerant fiowing into-thesupercharging evaporator 58. The evaporator 58 is positioned in a duct60 which opens at theupper end thereof into the charnher 27 as shown at61. The duct 66 is connected to an air well 62 constructed beneath. thebuilding unit It). The air well 62 provides a year around source of mildair, non mally in the neighborhood of 50 F. in temperate zones. Thismild air, though insuliicient in volume to provide the entire heatsource for the building unit it), is capable of producing sufficientmild ground air to operate the evaporator :78. Since the ground air isof a higher temperature than the outside air during the months when thesystem described here is used for heating, the supercharging evaporator58 may operate at a considerably higher pressure than the mainevaporator 13. The evaporator 58 feeds the vapor therein through a pipe63 which connects with the pipe 54 adjacent the supercharging port 55.The pipe 63 passes through the heat exchanger 56 and the vapor thereinreceives further heat from the refrigerant in the exchanger 56.Additional heat can be supplied from a water jacket 50a to the vapor inthe pipe 63. In this manner the heat carried from the condenser 20 bythe liquid refrigerant is removed to cool the liquid refrigerant flowingto the main. evaporator 18 sufficiently to allow that unit to operateefhciently. This heat is then added to already vaporized refrigerantused to supercharge the compression cylinder 32, whereby to increase theoutput of the condenser 20 and the intake of the evaporator .18.cylinder 32 through the lines 54 and 63, the pressure in the cylinder 32at the end of the intake stroke of the piston 33 can be increased fromabout 18 p. s. i. absolute to as much as 70 p. s. i. absolute, in theexample given ereinbefore. This, of course, results in a great increasein the heat radiating efiiciency of the condenser 20. In addition, theremoval of heat from the liquid going to the evaporator 18, results inan increase in the heat gathering It is possible that by superchargingthe capacity of the evaporator 18. 1 have found substantial increases inthe heat gathering efiiciency in tests of the machine.

To further increase this heat gathering capacity, a second heatexchanger 64 may be included in the line 51 and positioned in the groundair duct 60 as shown in Figure 2. With this constructiomheat remainingin the liquid flowing to the evaporator 16 after passing through theexchanger 50 may be extracted. This exchanger 64, however, only extractsa small portion of heat and may be omitted as in Figure 3, withoutsubstantial loss to the system. i i

As hereinbefore described, the main evaporator 13. is exposed to outsideair in the chamber 27 and extracts heat therefrom. Moisture in the airtends to collect on the evaporator 18, clogging the space between thefins 19 and restricting the flow of air through the chamber 27. Thisfrost reduces the efficiency of the evaporator 18, so it is desirable toprovide means for defrosting the evaporotor 13 at intervals. The presentinvention includes a defrosting mechanism which will quickly andautomatically defrost the evaporator 18 when necessary. I have foundthat such defrosting may be quickly accomplished by merely terminatingthe operation of the system for a few minutes, during which time themild ground air is drawn over the coils of the evaporator 18 to melt theice thereon. A spray of relatively warm water may be included to speedthe defrosting. The means for accomplishing this result will now bedescribed.

in the chamber 27, two temperature sensitive elements 65 and 66 arepositioneione on the upstream side of the evaporator 18 and onecontacting the evaporator, as shown in Figure 2. The bulbs 6:3" and 66have lines 67 and 63 leading from the top thereof to a control unitgenerally indicated at These bulbs 65 and 66, shown more clearly inFigure 6, are partially filled with a liquid and contain in addition,vapor of the same substance. As the temperature of the substance in thebulbs and 66 changes, the vapor pressure in the bulbs changes, in accordance with well known principles. In the control unit 69 andconnected to the lines 67 and 68 are two opposed diaphragms 70 and 71(see Figure 6), which are connected together by arod 72. It will beunderstood that if the temperature of the bulb 65 and the temperature ofthe evaporator 18 contacting the bulb 66 remain equal, the pressures inthe diaphragms 70 and 71 will remain equal and there will be no movementof the rod 72. Hot ever, should a temperature difierential exist betweenthe bulbs 65 and 66, the diaphragm of the bulb subjected to the highesttemperature will expand and push the rod 72 toward the other diaphragm.With the bulbs 65 and 66 positioned as shown in Figure 2, the bulb 65will be at the temperature of the air before heat is extracted by theevaporator 18, while the bulb 66 will be at the temperature of theevaporatorltl. As the evaporator 13 ices up, iess and less air will beallowed to pass through the chamber 27 and consequently there will be agreater temperature drop in the air that does pass, causing a greatertemperature differential between the bulbs 65 and 66. The bulb 65 alwaysbeing at the higher temperature, will tend to expand the diaphragm 70 tomove the rod 72 toward the diaphragm 71. A bias spring 73 preventsactual motion until the temperature differential reaches a predeterminedamount, but when this amount is exceeded, indicating considerable icingof the evaporator 13, motion will occur. Movement of the rod 72 willactuate a switch 74, shown in Figure 6, moving it from a normally closedcontact 75 to a normally open contact 76. The switch 74 is connected toa line 77 which extends to the voltage source. The normally closedcontact 75 is connected to a line 73 which leads through a time delayswitch 79 to a relay 8%). The switch 80a of the relay 80 is interposedin a line 81 extending from the voltage source to the motor 17 of thecompressor 18, and to the hot air circulation fan 26. V hen the relay 80is energized, the compressor motor 17 and fan 26 are energized. When theswitch 74 disengagcs from the contact 75, the relay 80 is deenergized,stopping the compressor 16 and fan 26. At the same time the cornpressor16 is stopped, it is necessary to close off the source of outside airfrom the chamber 27, and to open the chamber 27 to the ground air duct60 to permit the mild ground air to pass around the evaporator 1.8 andmelt the ice thereon. To accomplish this, I provide a damper 82,positioned as shown in Figures 2 and 3 at the entrance to the chamber27. When the damper 82 is in the position shown in Figure 2, it permitsoutside air to enter the chamber 27 while blocking an opening 83 fromthe duct 60. The damper 82 is connected to a reversible motor 84 whichhas a clockwise winding and counterclockwise winding. Thecounterclockwise winding. connected by a line 85 to the line 81supplying power to the compressor motor 17 and fan 26. A spring closedswitch 86 is interposed in the line 85 and positioned on the wall of thechamber 27 above the opening 83 leading to the duct 60. When the switch74 is engaged with the contact 75 and the compressor 16 is operating,the motor 34 will drive counterclockwise to swing the damper 82 to shutthe opening 83 until the damper engages and opens the switch 86. Theclockwise winding of the motor 84, however, is connected by a line 87 tothe normally open line switch contact 76. A spring closed switch 88 isinterposed in the line 87 and positioned as shown in Figure 2, on thewall of the chamber 27 above the entrance of the outside air duct 26.When the switch 74 is moved against the contact 76 in defrost position,current will flow through the line 87 and drive the motor 84 clockwiseuntil the damper' 82 closes the entrance to the duct 28 and opens theswitch 88. In this position, the damper S2 permits the mild ground airto pass over the evaporator 18.

'7 In order to prevent any flow of refrigerant through the evaporator 18during defrosting, a solenoid valve 89 is positioned in the line 51ahead of the expansion valve 52. The solenoid valve 89 is connected by alead 90 to the switch contact 75 so that when the switch 74 swings tothe defrost position, the solenoid valve 89 is deenergized and closed.

When the defrosting is completed, the large temperature differentialbetween the bulbs 65 and 66 will be decreased, and the rod 72, aided bythe bias spring 73 will move the switch 74 back to the normally closedcontact 75. At this time, however, considerable moisture may stillremain on the evaporator fins 19, so it is undesirable to flow cold airover the fins 19 at once. The time delay switch 79 placed in the line 78prevents the damper and corn pressor motors 84 and 17 from beingenergized immediately, and gives the moisture time to run oil. Thisswitch 79 consists of a bi-metallic switch 79a, which is closed whenheated, and a heater 7%. When the current through the line 78 isinterrupted during defrosting, the switch 79a cools and opens. When theswitch contact 75 is engaged after defrosting, current is passed throughthe heater 7%. After sufiicient time has elapsed to heat the switch 79a,it closes to start the motors 17, 26 and 84.

As shown in Figure 6, the lead 77 which supplies line current to theswitch 74, extends to one contact of a switch 91 which controls theoperation of the unit as either a heating or cooling unit. When theswitch 91 is in the position shown in Figure 6, the defrosting mechanismis energized for use during heating. The solenoid valve 38 is conectedto the lead '77 so as to be energized during heating to open the pipe 36and maintain the reversing valve 22 in the heating position. A solenoidvalve 92, positioned in the pipe 54, is also electrically connected tothe line 77 so that it is energized to open the pipe 54 during heating.When the unit 15 is to be used for cooling, the switch 91 is turned tothe opposite position where it connects the voltage source to a lead 93extending to a relay 94. The switch 94a of the relay 94 is interposed ina line 95 which extends from the voltage source to the compressor motor17 and fan 26. When this relay 94 is energized, the motors 17 and 26 areenergized through line 95. The line 85 to the counterclockwise windingof the damper motor 84 is connected to line 95 so that when the switch91 is turned to cooling position, the damper motor 84 will swing thedamper 82 to close off the entrance 83 from the duct 60. The defrostingmechanism and the solenoid valve 38 are deenergised and valve 38 isclosed.

The solenoid valve 39, however, is connected to the lead 93 and isenergized to open the pipe 37 and to cause the reversing valve 22 tomove to the position shown in Figure 3. The solenoid valve 92,positioned in the line 54, is also deenergized to close the pipe 54,since during the period when the unit 15 is operating as a coolingsystem, supercharging is unnecessary. The fan 30, positioned in thechamber 27, is intended to operate at all times, including thedefrosting periods, so it is electrically connected, through a lead 96to the voltage source. A switch 97 is interposed in the line 96 andganged with the switch 91. The switch 97 is so connected as to close theline 96 when the switch 91 is in either the heating or cooling position.

Figure 7 illustrates a somewhat modified circuit for V the unit 15wherein defrosting is accomplished in a different manner. With thecircuit illustrated in Figure 7, the defrosting switch 74 operatesbetween a normally closed contact 75 and a normally open contact '76 inthe same manner as shown in Figure 6 and controls the motors 17, 26 and84 and the solenoid valve 89 through circuit elements 78, 79, 80, 81,85, 86, 87, 88 and 90, as in the circuit shown in Figure 6. However, theoperation of the switch 74 is different. In the form of the inventionshown in Figure 7, the switch 74' is ganged to a switch 98a of a relay98. One side of the relay 98 and the switch 98a are connected by a lead99 to the contact of a single pole, single throw switch 100, the otherside of which is connected to a line 101 which extends to one contact, aheating and cooling control switch 91' which serves the same function asthe switch 91, that is, to switch the unit 15 to either heating orcooling position. The switch is connected to a control rod 102 which inturn is connected to a diaphragm 103. The diaphragm 103 is connected bya pipe 104 directly to the evaporator 18. With this construction, thevapor pressure in the evaporator 18 is communicated to the diaphragm103. So long as suflicient vapor pressure exists in the evaporator 18the pressure of the diaphragm holds the switch 100 closed, allowingcurrent to flow from line 101 through line 99 to the relay 98,maintaining both the ganged switches 98a and 74' in their normallyclosed positions. However, should the pressure in the evaporator 18 fallbelow a predetermined level, a bias spring 105 will force the diaphragm103 to partially collapse and allow the switch 100 to open. In thisevent current will no longer flow to the relay 98 through the lead 99.The relay will not, however necessarily be deenergized, for an alternatecurrent path is provided by a lead 106 which extends to the switch 98aof the relay 98 from the current supply line 101. This lead 106 hasinterposed therein a cam operated switch 107 which is opened and closedat selected intervals by a cam 108 driven by a motor 109. If, at thetime the switch 100 is opened by insufficient pressure in the evaporator18 (caused by icing conditions), the switch 107 is closed, the relay 98will remain energized by current flow through its own switch 98a. Untilthe next periodic opening of the switch 107, the relay 98 will remainenergized and the defrosting switch 74 will remain in normally closedposition. If the switch 107 opens while the switch 100 is open, then,and only then, will defrosting occur. This circuit provides fordefrosting based upon the pressure within the evaporator 18, butprovides for protection against accidental defrosting caused bytransient pressure fluctuations in the evaporator 18 caused by otherthan icing conditions. In the modified circuit, the fan 30 is energizedthrough a line 96 controlled by a switch 97" ganged with switch 91'substantially as in the circuit of Figure 6.

If desired, the defrosting may be augmented by a spray of water from awater pipe 110 mounted above the evaporator 18. The pipe 110 has asolenoid operated valve 111 therein which is electrically connected tothe switch contact 76 or 76', as shown in Figures 6 and 7. When theswitch 74 or 74 moves against contact 76 or 76 in the defrost position,the valve 111 is energized and opened to spray water over the evaporator18 to assist in defrosting. The valve is closed when the switch 74 or 74' returns to normal position.

Figure 3 illustrates the operation of the unit 15 as a summer coolingsystem. When the unit 15 is to be so used, the switch 91 or 91 is turnedto the cooling position so as to cut out the defrosting mechanism, closethe solenoid valves 38 and 92, open the valve 39, and insure that thedamper 82 is moved to close the mild air opening 83. Now, compressedrefrigerant flows from pipe 34 through pipe 37 and reverses the valve 22by positively seating valve 41 against its seat 41b. The hot compressedrefrigerant vapor is then passed through port 41d and into the member 18which now operates as a condenser, cooled by the outside air inthechamber 27. The condensed and cooled refrigerant flowing from the member18 cannot flow into the line 51 due to the check valve 53, so a pipe 112is provided which connects to the member 18 adjacent the expansion valve52. The pipe 112 carries the refrigerant to the' receiving vessel 48.The check valve 113 in the line 112 prevents flow from the receiver 48to the member 18 during heating operations. From the receiver 48 theliquid refrigerant flows through line 49, exchanger 50 and into line 51and the second heat exchanger 64 where it is cooled by the mild air inthe duct 60. There is no flow of vapor-through the pipe 54 due to theclosed solenoid valve 92, nor is there flow in the pipe 46 toward thesupercharging evaporator 58 due to the check valve 46b.

The cooled liquid in the pipe 51 cannot enter the member 18 throughcheck valve 53 and expansion valve 52 because of the high pressure vaporin the member 18, so a pipe 114 is provided which connects to the pipe51 just ahead of the check valve 53. The pipe 114 extends to the lowerend of the member 20 adjacent the connection thereof with the pipe 45. Athermal regulating expansion valve 115111 the pipe 114 expands the coldliquid refrigerant as it enters the member 20. The member 20 now acts asan evaporator, and heat is removed from the air in the bonnet 23. Thevapor passing from the member 20 flows through port 40d in the valve 22and into the return line 43, to be drawn into the cylinder 32 upon theintake stroke of the piston 43.

It is believed clear from the foregoing that my improved mechanismoperates efliciently either as a heating or cooling system, and that theconversion from heating to cooling is accomplished by turning a singleelectrical switch 89.

While it is desirable toutilize outside air partially preheated in theattic space as the main heat source, and to augment this heat sourcewith mild air from a ground air well, it is contemplated, in instanceswhere a ground air well cannot be provided, that the main heating air bedrawn directly from outside, and attic air and water be used as the mildheat source for supercharging and defrosting. In such a case, thedecreased volume of air drawn from the attic space would allow a higherattic temperature to be maintained, and the attic air utilized in thesystem would be at a temperature sufficient for defrosting purposes.

In either arrangement the completed air conditioning system utilizes oneair conduit circuit comprising ducts 24 and 25 and the bonnet 23 forcirculating air through the dwelling area 12. It uses a second airconduit circuit, including the inlet pipe 28 and the discharge pipe 31for drawing outside air into the dwelling and discharges it outside ofthe dwelling. The third air duct 60 draws air from the area (either theattic or the ground well), which because of its position relative to thedwelling, keeps air therein at a temperature above the outsidetemperature during the heating season. In the first instance the secondcircuit consists of conduits 28 and 31 which also takes air that isheated from the dwelling, while the conduit 60 of the third air circuittakes mild air from the ground beneath the dwelling. In the situationwhere r a ground air well cannot be provided, the conduit 28 would takeits air directly from outside the dwelling and the attic where it wouldbe drawn in through the conduit 60. In both instances there is one airduct circuit for circulating air through the dwelling area, which duringthe heating cycle, contains the condenser. There is a second air ductcircuit taking outside air through the system and dischargingit to theexterior of the dwelling and this circuit has the evaporator therein toextract heat from the outside air during the heating cycle. There isalso a third air conduit circuit which receives its air from the area(attic or air well) which supplies heat to keep the air above theoutside air temperature during the heating season. This third circuitalso has an evaporator in it where heat is picked up to supply arefrigerant vapor as a supercharge to the compressor.

It is believed that the nature and advantages of the invention appearclearly from the foregoing.

Having thus described my invention, I claim:

1. An air conditioning system for dwellings having an attic area overthe dwelling area into which air may be drawn and having abasement areainto which air may be drawn from the earth, said system comprisingan airduct circuit for circulating air through the dwelling area from thebasement area, a condenser in the basement area and within said air ductcircuit, a second air duct circuit taking outside air through the atticarea to the basement area and from the basement area to the exteri or ofthe dwelling, an evaporator in the basement area within said second airduct circuit, a third air duct circuit in the basement area connected tothe second air duct circuit to discharge air to the evaporator andhaving an inlet drawing air from the earth, a compressor operativelyconnected to said condenser and evaporator to draw refrigerant vaporfrom the evaporator and compress it and discharge it into thecon-denser, a second evaporator in said third air duct circuit, arefrigerant carrying pipe leading from said condenser having one branchpipe leading to said first named evaporator and having a second branchpipe leading to the second evaporator, said second evaporator having anoutlet pipe leading to the compressor, and the first named branch pipebeing in heat exchange relation to the outlet pipe whereby to transferheat from condensed refrigerant to the evaporated refrigerant in saidoutlet pipe.

2. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air,

because of the position of said second area relative to the dwelling,receives heat to keep it at a temperature above outside air temperature,said system comprising an air duct circuit for circulating air throughsaid dwelling area, a second air duct circuit drawing outside air intothe dwelling and discharging it outside of the dwelling, a condenser inthe first said air duct circuit, an evaporator in the second air ductcircuit, a third air duct circuit leading from said second area anddischarging into said second air duct circuit, a compressor operativelyconnected to said condenser and evaporator to draw refrigerant vaporfrom the evaporator, compress said vapor and discharge it into thecondenser, means to return condensed refrigerant to said evaporator, asecond evaporator in said third air duct circuit, a refrigerant carryingpipe directing a part of the condensed refrigerant to the secondevaporator, said second evaporator having an outlet pipe leading to thecompressor, said means including a conduit for refrigerant in contactwith said outlet pipe whereby to transfer heat from condensedrefrigerant to the evaporated refrigerant in said outlet pipe.

3. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, air cut-off means operable, in response to iceformation on said evaporator, to restrict the flow of air past saidevaporator to air in said third air duct circuit, a compressoroperatively connected to said condenser and evaporator to drawrefrigerant vapor from the evaporator, compress said vapor and dischargeit into the condenser, means to return condensed refrigerant to saidevaporator, a second evaporator in said third air duct circuit, arefrigerant carrying pipe directing a part of the condensed refrigerantto the second evaporator, said second evaporator having an outlet pipeleading to the compressor, said means including a conduit forrefrigerant in contact with said outlet pipe whereby to transfer heatfrom condensed refrigerant to the evaporated refringement in said outletpipe.

4. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, hecause of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a

I second air duct circuit drawing outside air into the dwelling anddischarging it outside of the dwelling, a condenser in the first saidair duct circuit, an evaporator in the second air duct circuit, a thirdair duct circuit leading from said second area and discharging into saidsecond air duct circuit, air cut-01f means operable, in response to iceformation on said evaporator, to restrict the flow of air past saidevaporator to air in said third air duct circuit, a compressoroperatively connected to said condenser and evaporator to drawrefrigerant vapor from the evaporator, compress said vapor and dischargeit into the condenser, means to return condensed refrigerant to saidevaporator, a second evaporator in said third air duct circuit, and arefrigerant carrying pipe directing a part of the condensed refrigerantto the second evaporator, said second evaporator havin an outlet pipeleading to the compressor.

5. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to said condenserand evaporator to draw refrigerant vapor from the evaporator, compresssaid vapor and discharge it into the condenser, and means to returncondensed refrigerant to said evaporator, said means including a conduitin said third air duct circuit operable to transfer heat between thecondensed refrigerant and the air in said third air duct circuit.

6. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to said condenserand evaporator to draw refrigerant vapor from the evaporator, compresssaid vapor and r discharge it into the condenser, and means to returncondensed refrigerant to said evaporator, said means including a storagevessel for condensed refrigerant having a bottom outlet to saidevaporator and a top outlet leading to the compressor, the compressorhaving its chamber provided with an opening to said outlet uncovered tothe compression chamber only at the finish of the in-take stroke of thecompressor.

7. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to said con-denserand evaporator to draw refrigerant vapor from the evaporator, compresssaid vapor and discharge it into the condenser, and means to returncondensed refrigerant to said evaporator, said means including a storagevessel for condensed refrigerant having a bottom outlet to saidevaporator and a top outlet leading to the compressor, the compressorhaving its chamber provided with an opening to said outlet uncovered tothe compression chamber only at the finish of the iii-take stroke of thecompressor, said outlet having a venturi restriction therein, and theevaporator to compressor connection ineluding a bypass to saidrestriction provided with a check valve limiting flow through saidbypass to the condition when vapor fiow through the venturi restrictiondrops the pressure in said bypass below the pressure in the evaporatorto compressor connection.

8. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to said condenserand evaporator to draw refrigerant vapor from the evaporator, compresssaid vapor and discharge it into the condenser, and means to returncondensed refrigerant to said evaporator, said means including a storagevessel for condensed refrigerant having a bottom outlet to saidevaporator and a top outlet leading to the compressor, the compressorhaving its chamber provided with an opening to said outlet uncovered tothe compression chamber only at the finish of the in-take stroke of thecompressor, said means also including an evaporator in said third airduct receiving a part of the condensed refrigerant, and having itsdischarge connected to said opening to the compression chamber.

9. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to said condenserand evaporator to draw refrigerant vapor from the evaporator, compresssaid vapor and discharge it into the condenser, means to returncondensed refrigerant to said evaporator, temperature sensitive elementsresponsive one to the evaporator temperature and the other to the airtemperature on the upstream side of the evaporator, control meansoperably connected to said elements to stop the compressor upon increasein temperature difference between the evaporator and the upstream airabove a predetermined amount, and an air damper in said second ductupstreamfrom the evaporator o-perably connected to the control means toclose said second duct when the compressor is stopped.

10. An air conditioning system for dwellings having therein a dwellingarea, and a second area in which air, because of the position of saidsecond area relative to the dwelling, receives heat to keep it at atemperature above outside air temperature, said system comprising an airduct circuit for circulating air through said dwelling area, a secondair duct circuit drawing outside air into the dwelling and dischargingit outside of the dwelling, a condenser in the first said air ductcircuit, an evaporator in the second air duct circuit, a third air ductcircuit leading from said second area and discharging into said secondair duct circuit, a compressor operatively connected to it into thecondenser, means to return condensed refrigerant to said evaporator, asecond evaporator in said third air duct circuit, a refrigerant carryingpipe directing a part of the condensed refrigerant to the secondevaporator, said second evaporator having an outlet pipe leading to thecompressor, said means including a conduit for refrigerant in contactwith said outlet pipe whereby to transfer heat from condensedrefrigerant to the evaporated refrigerant in said outlet pipe, and awater jacket around References Cited in the file of this patent saidoutlet pipe having means to direct water into heat 10 2,716,870

exchange relation to said outlet pipe.

UNITED STATES PATENTS Buchanan a. July 12, Ambrose Aug. 18, Clancy June28, Silvestro Feb. 12, Jones Jan. 19, Gygax June 8, Biehn Sept. 6,Borgerd et al. June 12,

